OTTAWA - Climate talks have gone into overtime at a United Nations summit in South Africa.

Negotiators from nearly 200 countries are trying to salvage a compromise deal that sets the world on a path to ink a new climate treaty by 2015 to replace the expiring Kyoto Protocol.

But according to text of the proposed pact, legal obligations to lower greenhouse gases would not kick in until sometime after 2020. Environmentalists and some scientists say that is too long to wait for binding action on global warming.

Still, the proposal is the only one the world's two top polluters, the United States and China, are likely to agree to after two weeks of difficult negotiations in the South African port city of Durban.

The pitch also seems intended to win the support of countries such as Canada, which refuses to sign on to a second Kyoto commitment period after the world's only binding climate treaty expires at the end of next year.

Environment Minister Peter Kent urged other countries to forget about Kyoto and instead focus on inking a new global treaty within the next few years that binds all the world's big polluters.

"We are pressing toward the finish on a number of items," Kent said late Friday in Durban, adding that the Canadian government stand is "fair, effective and comprehensive."

"So it's down to the wire with Canada saying -- as our Conservative government has all along -- that global issues require global solutions. We need a single new climate change pact that covers all major emitters."

Kent had floated 2015 as a flexible deadline for a new deal to replace Kyoto.

Under the terms of the proposed plan, the European Union would extend its Kyoto commitment beyond next year and all other countries would agree to negotiate a new treaty with legally binding obligations for everyone -- including big polluters such as the U.S., China and India.

There were reports Friday that China had balked at those conditions.

China and India are part of a group of emerging powers that argued they are still developing nations and therefore should not face the same kind of binding commitments as wealthy countries.

Under Kyoto, rich countries are legally bound to lower their greenhouse gases while developing countries do so voluntarily.

Meanwhile, the European Union, the world's poorest countries and a group of small island states said the time for climate talk is over and now it's time for action.